Effective therapy for periprosthetic joint infection through sequential application of non-contact low-frequency...

Conventional mechanical debridement may be insufficient to fully eradicate biofilms adherent to prosthetic and surrounding tissue surfaces in cases of periprosthetic joint infection (PJI). This study aimed to evaluate the eradication efficacy and safety of non-contact low-frequency ultrasonic debridement (NLFUD) combined with antiseptic solutions against Staphylococcus aureus biofilms.

Ex vivo, sequential NLFUD was followed by one of four antiseptic protocols (0.9% saline, 3% H₂O₂, 0.5% povidone-iodine (PI), or 3% H₂O₂ then 0.5% PI) to eliminate S. aureus biofilms on titanium discs, and evaluated eradication efficacy by live/dead staining and scanning electron microscopy (SEM). In vivo, the approach was subsequently evaluated in a S. aureus-infected PJI rat model comprising four groups: mechanical debridement alone, mechanical and chemical debridement, mechanical and NLFUD debridement, and combined mechanical, NLFUD, and chemical debridement. In vivo, biofilm disruption was assessed by SEM, and safety by haematology, hepatorenal function, major-organ histology, local angiogenic/inflammatory markers, and periprosthetic bone integration.

NLFUD combined with each antiseptic produced residual live and dead biofilm areas of < 1%. NLFUD + PI and NLFUD + H₂O₂ + PI groups exhibited no bacterial regrowth. SEM analysis confirmed effective biofilm disruption using NLFUD on titanium discs ex vivo and on titanium alloy prosthesis in vivo. NLFUD treatment significantly increased bacterial counts in surgical fluid (median 2,665 vs 195 CFU/ml, p = 0.002). Biofilms were reformed in all groups at two weeks after debridement surgery. No significant between-group differences were seen in local immunohistochemical markers (including periprosthetic bone integration and angiogenic markers), or systemic inflammatory indicators, and haematoxylin and eosin staining revealed no structural abnormalities in major organs.

As an intraoperative adjunct to debridement in PJI, sequential NLFUD and antiseptic irrigation enhance immediate biofilm disruption while maintaining a favourable systemic and local safety profile, warranting clinical evaluation to reduce residual biofilm burden.